@jmbell1989 See https://docs.duet3d.com/en/User_manual/Reference/Gcodes#checking
According to the above, it will only produce an error if either line number or checksum is missing. Otherwise, if the checksum is different from the one the firmware calculates, it's waiting on the request to repeat transmission of the line. I guess this eventually times out. I don't think there's any way around this behaviour; I've asked @dc42. I have also asked what CRC-16 algorithm is used to calculate the checksum, as there are quite a few different ones.
Ian